FAN5616

FAN5616 High-Efficiency, Constant-Current LED Driver with Adaptive Charge Pump

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FAN5616 High-Efficiency, Constant-Current LED Driver with Adaptive Charge Pump

November 2005

FAN5616 High-Efficiency, Constant-Current LED Driver with Adaptive Charge Pump
Features
3-Channel Parallel LED Driver for a Large Range of

Description
The FAN5616 generates a regulated output current from a battery with an input voltage between 2.7V to 5.5V. Switch reconfiguration and fractional switching techniques are utilized to achieve high efficiency over the entire input voltage range. The adaptive nature of the built-in charge pump eliminates the need for LED preselection (matching) and ensures operation with high efficiency. The driver s built-in, proprietary, auto-sense circuitry ensures the same high efficiency regardless of the number of LEDs. When the input voltage is sufficiently high to sustain the LED s programmed current level, the FAN5616 reconfigures itself to operate as a linear regulator, and the charge pump is turned off. The FAN5616 supports both digital and PWM LED brightness control methods. The built-in 2-bit DAC offers a selection of four LED current levels, each level is a percentage of the maximum LED current set by the external RSET resistor. The FAN5616 includes built-in shutdown, short circuit and thermal protection circuitry
. A built-in smart soft-start circuitry prevents excessive current draw during power on while allowing for an increased PWM frequency for dimming. Minimal external components are required. Only two 0.1 F to 1 F bucket capacitors, a 4.7 F input capacitor and a 1 F output capacitor are needed for proper operation. The FAN5616 is available in a 3x3mm 16-lead MLP package.

Forward Voltages Adaptive VOUT Adjustment to the Highest Diode Forward Voltage Internally Matched LED Current Sources Matched LED Currents with Matched or Unmatched LEDs Built-in Charge Pump with Three Modes of Operation: 1x, 1.5x, and 2x Up to 90% Efficiency Up to 50kHz PWM Dimming Frequency Low EMI, Low Ripple Up to 120mA Output Current Drives up to 3 LEDs at 40mA each External Resistor to Set Maximum (100%) LED Current Built-in 2-bit DAC to Control LED Current in Digital Mode 2.5V to 5.5V Input Voltage Range ICC 1 A in Shutdown Mode 1MHz Operating Frequency Shutdown Isolates Output from Input Smart Soft-Start Limits In-Rush Current Short Circuit Protection Minimal External Components Needed Available in a 3x3mm 16-lead MLP Package

Applications
Cell Phones PDAs, DSCs, and MP3 Players

Ordering Information
Product Number
FAN5616

Package Type
3x3mm 16-Lead MLP

Order Code
FAN5616MPX

2005 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN5616 Rev. 1.0.0